Addition of Swarf to Produce a Semi-Solid Slurry during High Pressure Die-Casting of AS9U3 Aluminum Alloy
An internal cooling agent is used in rapid slurry forming (RSF) process to produce a high solid fraction slurry for a short period of time. In the process used in this research, the swarf which is known to be a low enthalpy material was added to the melt as the internal cooling agent. During the process, the swarf started to melt and a semi-solid slurry with a relatively high solid fraction was formed. This slurry was formed by exchanging the enthalpies between the low and high enthalpy materials. A commercial Al-Si-Cu alloy, i.e. AS9U3 Aluminum alloy, was used in this investigation. The microscopic examination showed that the Al-Si eutectic colonies start to melt during the melting process of swarf material resulting in the formation of globular Alpha-Al grains due to the multiplication of secondary dendrites arms. The fracture of dendrites arms and the subsequent spheroidization were suggested to be the origin of non-dendritic globular grains in the final microstructure. The amount of primary globular Alpha-phase was measured by the image analysis software. The results showed that during high pressure die-casting of AS9U3 Aluminum alloy using 4 mm thick samples, around 35 percent solid has been formed at the temperature of 580 oC.
Qiang Zhu, Ahmed Rassili, Stephen P. Midson and Xiao Gang Hu
H. Hadian et al., "Addition of Swarf to Produce a Semi-Solid Slurry during High Pressure Die-Casting of AS9U3 Aluminum Alloy", Solid State Phenomena, Vol. 285, pp. 271-276, 2019